package main

import "fmt"

func main() {
	map1 := map[string]int{"a": 1, "b": 2, "c": 3}

	map1["a"] = 456

	fmt.Println("map1", map1)

	for _, value := range map1 {
		fmt.Println("map-value", value)
	}

	a, some := map1["d"]

	if some {
		fmt.Println("a", a)
	} else {
		fmt.Println("none", a == 0)
	}
}
